To me the big drop in noticable internal politics happened somewhere shortly before or around the Overwatch release.

The original design of that game as-released showed a lot of the old design paradigms of Blizzard. But then all post-release direction was the “new” Blizzard, focus on e-sports, numerical balance over gameplay feel, competition over social engagement. The game is an interesting showcase for the fall of Blizzard as a whole in a lot of ways.